Question

我将RecyclerView与GridLayoutManager一起使用。用户可以在2到4之间切换跨度计数，这将生成一个动画，该动画将每个单元格的内置转换动画运行到新位置。到目前为止，我一直在使用的代码是：

TransitionManager.beginDelayedTransition(moviesGridRecycler);
gridLayoutManager.setSpanCount(NEW_SPAN_COUNT);
adapter.notifyDataSetChanged();

这对我来说很好，但是现在我需要为每个跨度计数使用不同的布局。为此，我在RecyclerView中有2种视图类型，由于移动到新的跨度计数时视图类型已更改，因此RecyclerView无法看到它是“相同”的内容，并且默认不运行翻译动画。

如果启用布局过渡，则将获得视图输入动画，而不是视图位置更改动画。两个跨度计数的单元格视图的宽度和高度分别为match_parent和wrap_content。

作为替代方案，我尝试将新的视图类型全部放在一起，只使用一种视图类型。我有一个FrameLayout，其中包含两个跨度计数的视图。在onBindViewHolder()中，我只是切换子视图的可见性。这也不会产生动画。

我关注了this thread和this one，但是无法解决我的问题。

完整代码：

    class ItemFragment : Fragment() {
    private var spanCount = 2
    lateinit var recyclerView: RecyclerView
    lateinit var button: Button

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        val view = inflater.inflate(R.layout.fragment_item_list, container, false)
        recyclerView = view.findViewById(R.id.listView)
        recyclerView.apply {
            adapter = MyItemRecyclerViewAdapter(DummyContent.ITEMS, spanCount)
            layoutManager = GridLayoutManager(context, spanCount)
            addItemDecoration(RecyclerGridDecoration(context))
        }
        button = view.findViewById(R.id.toggle)
        button.setOnClickListener { onToggle() }

        return view
    }

    fun onToggle() {
        spanCount = if (spanCount == 2) 4 else 2
        TransitionManager.beginDelayedTransition(recyclerView)
        (recyclerView.layoutManager as GridLayoutManager).spanCount = spanCount
        (recyclerView.adapter!! as MyItemRecyclerViewAdapter).apply {
            span = spanCount
            notifyDataSetChanged()
        }
    }

}



class MyItemRecyclerViewAdapter(
        private val mValues: List<DummyItem>,
        var span: Int)
    : RecyclerView.Adapter<MyItemRecyclerViewAdapter.ViewHolder>() {


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        if (viewType == 2) {
            val view = LayoutInflater.from(parent.context)
                    .inflate(R.layout.items_two, parent, false)
            return TwoViewHolder(view)
        } else {
            val view = LayoutInflater.from(parent.context)
                    .inflate(R.layout.items_four, parent, false)
            return FourViewHolder(view)
        }

    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val item = mValues[position]
        if (holder is TwoViewHolder) {
            holder.textTwo.text = item.content
        } else if (holder is FourViewHolder) {
            holder.textFour.text = item.content
        }
    }

    override fun getItemCount(): Int = mValues.size

    abstract inner class ViewHolder(mView: View) : RecyclerView.ViewHolder(mView)

    inner class TwoViewHolder(mView: View) : ViewHolder(mView) {
        val image: ImageView = mView.imageTwo
        val textTwo: TextView = mView.textTwo

    }

    inner class FourViewHolder(mView: View) : ViewHolder(mView) {
        val textFour: TextView = mView.textFour
    }

    override fun getItemViewType(position: Int): Int {
        return span
    }
}

Answer 1

对于您的问题，我有解决方案，将您的切换功能更改为：

  fun onToggle() {
        spanCount = if (spanCount == 2) 4 else 2
        (recyclerView.adapter!! as MyItemRecyclerViewAdapter).apply {
            span = spanCount
            notifyDataSetChanged()
        }
recyclerView.post(object:Runnable {
  public override fun run() {
     TransitionManager.beginDelayedTransition(recyclerView)
        (recyclerView.layoutManager as GridLayoutManager).spanCount = spanCount
  }
})
   }

在上面的代码中，我们首先更改recyclerView的viewType，然后更改RecyclerView UI Handler Queue上GridLayoutManager的spanCount，以便依次实现两个UI操作。

列数更改时对Recycler View网格进行动画处理

1 个答案: